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Study challenging IPCC: 300-year-old sponges show over 1.5 °C warming.

Today is Friday, February 16, 2024.

Over one year ago we posted "About pollution, wood and others in England in 1833 and 1847", when we selected a few quotes that appear in the book “The Essential Writings of Ralph Waldo Emerson”, including very interesting testimonies about some of his travels. Worth reading again. After the quotes we added the following information to give perspective of what was being said about those times:

  • "the world's first oil well was drilled in 1859 in United States, i.e. after Emerson’s visits to England.

  • the concentration of CO2 in the atmosphere at that time was around 260 ppm. Current concentration is about 415 ppm.

  • as Emerson indicated, the global population then was estimated about 1,1 billion people. Around 1950, it reached 2 billion. And a few weeks ago, 8 billion. This means that the World population multiplied by 8 in the last 190 years."

Then, in one of our first 2024 posts, "Albedo. The Earth is darkening", we quoted an article from NASA that started as follows:

"When the mercury thermometer was invented in 1714, it took the scientific world by storm. On his transatlantic crossing in the year 1724, Benjamin Franklin recorded water temperatures by periodically dipping a thermometer into the ocean. By 1850, weather stations across the globe had gleaned a record of air temperatures over land. For the first time, scientists could track Earth’s temperature. And over time, it became clear that temperature was rising."

After setting the scene with these quotes, we want to refer to a recent study published at Nature, in which scientists analyised 300 years of our planet's temperature throgh sclerosponges.

In other words, using 300 years of ocean mixed-layer temperature records preserved in sclerosponge, they measured the ratio of two elements — calcium and strontium — in the skeletons of Ceratoporella nicholsoni, making the coral-like sponges a proxy thermometer, reflecting changes in water temperature.

During a relatively stable period from 1700 to 1860, global sea surface temperatures varied by less than 0.2 °C — with the notable exception of brief cooler periods attributed to volcanic eruptions. This would suggest a different baseline for pre-industrial global mean temperatures, for example, considered by the Intergovernmental Panel on Climate Change (IPCC).

As a consequence, this thermometric study would show global warming already exceeding 1.5 °C, a key target of the Paris Agreement. The result is 0.5 °C higher than IPCC estimates, with 2 °C global warming projected by the late 2020s, nearly two decades earlier than expected.

Click at the image below for the study by McCulloch, M.T., Winter, A., Sherman, C.E. et al. "300 years of sclerosponge thermometry shows global warming has exceeded 1.5 °C. at Nature Climate Change 14, 171–177 (2024). Its a study worth reading.


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“Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.”

“I am among those who think that science has great beauty”

Madame Marie Curie (1867 - 1934) Chemist & physicist. French, born Polish.

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